When creating directory specs, use srctop_dir rather than srctop_file.

While insignificant on Unix like systems, this is significant on
systems like VMS.
Reviewed-by: NRich Salz <rsalz@openssl.org>
Reviewed-by: NTim Hudson <tjh@openssl.org>

test/recipes/80-test_ct.t

 #! /usr/bin/perl
 
-use OpenSSL::Test qw/:DEFAULT srctop_file/;
+use OpenSSL::Test qw/:DEFAULT srctop_file srctop_dir/;
 use OpenSSL::Test::Simple;
 
 setup("test_ct");
 $ENV{CTLOG_FILE} = srctop_file("test", "ct", "log_list.conf");
-$ENV{CT_DIR} = srctop_file("test", "ct");
-$ENV{CERTS_DIR} = srctop_file("test", "certs");
+$ENV{CT_DIR} = srctop_dir("test", "ct");
+$ENV{CERTS_DIR} = srctop_dir("test", "certs");
 simple_test("test_ct", "ct_test", "ct", "ec");